Synchronizing apparatus



April 26, 1938.

S. TANIA] SYNCHRONIZING APPARATUS Filed May 9, 1936 Fig. I.

2 Sheets-Sheet l Inventor: Seiichi Tan'iai,

His Attorneg.

April 26, 1938. s. TANlAl SYNCHRONIZING APPARATUS Filed May 9, 1956 Fig. 2.

2 Sheets-Sheet 2 Fig.3.

Time

Inventor: Seiichi Taniai,

His Attorneg.

Patented Apr. 26, 1938 2,115,595

UNITED STATES PATENT OFFICE SYNCHRO-NIZING APPARATUS Seiichi Taniai, Yokohama, Japan, assignor to General Electric Company, a corporation of New York Application May 9, 1936, Serial No. 78,814 In Japan October 9, 1935 13 Claims. (Cl. 171-118) My invention relates to improvements in syncontrolled by a relay having normally open conchronizlng apparatus and has for an object the tacts which are closed when the relay is enerprovision of improved synchronizing apparatus gized. for so controlling the operation of connecting For controlling the closing of the circuit break- 5 two alternating current circuits as substantially to er 3 so as to effect a connection of the circuits l eliminate the possibility of effecting a connection and 2 under synchronous conditions thereof, any at the wrong instant. suitable manual or automatic means, examples In order to avoid any appreciable disturbance, of which are well known to the art, may be em- I two alternating current circuits should be conployed. I have chosen to illustrate an automatic 7 10 nected when their electromotive forces are submeans which is similar to the synchronizing ap- O stantially alike in phase and frequency. It is paratus disclosed in United States Letters Patent also preferable that they be substantially alike ,7 s ued August 14, 1928, but it Will be in magnitude. Inasmuch as the closing operation obvious that the application of my invention is takes an appreciable time, it is desirable to start not limited to this particular apparatus. Thus,

when the frequency difference is small enough a synchronizing relay 6 is connected to be ener- 5 and also sufficiently prior to phase coincidence to gized by corresponding voltages of the circuits I allow for the time necessary to make the connecand 2 through suitable means such as potential tion. The closing time of circuit breakers for transformers 1 and 8 so as to operate in dependhigh voltage, large capacity circuits is so long ence on the sum of and the difference between the that the frequency difierence may undergo such two voltages. The normally open contacts 9 and 2 changes as to render the completion of a closing ii o t s re y w close When the frequency 2O operation undesirable. This is also true, even Terence and the voltage and Phase difference with shorter closing-time circuit breakers, where tween the electro-motive forces of the circuits i the circuits are subject to large frequency variaand 2 are below predetermined values. Besides tions as, for example, in some low head hydraulic the synchronizing relay 6, there may be employed plants. Also errors in judgment of the operator an auxiliary synchronizing relay H whose. enerin manual. control or errors of the synchronizing sizin W di iS Connected to the Potential t device in either manual or automatic control may f0rmer5 T nd 3 S0 s to b energized in a cord make it undesirable to complete the closing operance with the vector difference between two coration. In order to eliminate the possibility of an responding electromotive forces of the circuits l undesirable closing, I provide, in accordance with and 2. This relay can be set to close its contacts my invention, means for determining the state of i2 when the phase difference between the elecsynchronism after the closing operation has been tromctive forces of the circuits is less than a prestarted such that if conditions are unfavorable, determined value. Thus, if the. contacts 9, H), the closing operation is interrupted or checked. and I2 of relays 6 and H are connected in series 30 My invention will be better understood from in a control circuit, as shown, the sticking of the the following description when considered in concontacts of one will not cause false synchronizing nection with the accompanying two sheets of if e Contacts 0f the other are p drawings, and its scope will be pointed out in the In order to obt in a c ntrol dependent on the appended claims. instantaneous positions of the contacts of the 40 In the accompanying drawings, Fig. 1 illussy c o ys 6 and N, there may be trates diagrammatically an automatic synchronused a normally open circuit-closing auxiliary reizing arrangement embodying my invention; lay l3, which has a resistance M in the circuit of Fig. 2 illustrates diagrammatically a modificats Operating Winding a po t of the resis- 5 tion of the embodiment of my invention Shown tance being short-circuited when the contacts in Fig. I; Fig. 3 is a switch closing time-travel and 0f the Synchronizing e ays a e curve explanatory of my invention; and Fig. 4 is simultaneously closed. For controlling the relays a voltage vector diagram explanatory of my in- 5 and I3, there may be provided a normally closed vention. circuit-opening relay 16 which opens and closes In Figs. 1 and 2, two alternating current cirits contacts I! with a definite time delay when its cuits l and 2 are arranged to be connected by operating coil 8 is energized and fi zed.

suitable switching means, such as a circuit break- For energizing the various control devices, there er 3, which is illustrated as having a mechaniis provided an auxiliary control bus CB which cally trip-free operating mechanism including a may be energized from a D. C. source. The operclosing coil 4. The circuit of this coil may be ating coil 15 of the auxiliary relay I3 is normally energized in a circuit from one side of the control bus CB through a conductor l 9, the resistance M, the winding l5 of the auxiliary relay l3, and the contacts I! of the time limit relay I6 to the other side of the control bus CB. However, as the resistance l4 limits the value of the current in this circuit, the auxiliary relay I3 is not sufliciently energized to close its contacts 20 and 2 I.

When the voltage and phase, and frequency differences between the eleotromotive forces of the two circuits l and 2 decrease to the values for which the synchronizing relays 6 and H are set to respond, their contacts 9, Ill and I2 will be closed at some instant. A part 22 of the resistance I4 in the circuit of the operating winding [5 of the auxiliary relay i3 is thereby shortcircuited and the operating coil I5 is energized sufficiently to cause the relay l3 to close its contacts 20 and 2|, thus completing the circuits of the control relay 5 and the time limit relay I6 respectively. Even though some one of the contacts 9, l9 and I2 opens the resistance l4 passes enough current to maintain the relay l3 in its contact closing position after it has been operated to this position. The circuit of the control relay 5 is from one side of the bus CB through the conductor IS, the operating coil 23 of relay 5, the contacts 20 of the auxiliary relay l3, and the contacts I! of the time limit relay IE to the other side of the bus CB. The energization of the control relay 5 effects the closing of the contacts 24 ofthis relay to complete the circuit of the closing coil 4 of the circuit breaker as follows: From one side of the bus CB through the conductor 19, the closing coil 4 and the contacts 24 of the control relay 5 to the other side of the bus CB, whereby to effect the closing of the circuit breaker 3. The time limit relay It will open its contacts I! a predetermined time after the circuit breaker 3 is closed to de-energize the operating coil 23 of the control relay 5 and the operating coil l5 of the auxiliary relay I3, These relays therefore open their contacts 24, 20 and 21. The opening of the contacts 2| de-energizes the operating coil I8 of the time limit relay i6, which returns to its normal condition to close its contacts after a predetermined time. This completes the synchronizing operation with the apparatus so far described.

The circuit breaker 3 does not close it contacts immediately upon energization of its closing coil but an appreciable time thereafter, which may be in case of large circuit breakers, a second or more. Thus as shown in Fig. 3, when the closing coil is energized, the operating mechanism of the circuit breaker will start its closing motion after an interval of time t. After another interval of time T, the contacts of the circuit breaker engage. Likewise, the relay 5, even though it is of the so-called instantaneous type, will not instantly close its contacts when its operating coil is energized but will require some time to close its contacts.

These intervals of time required for the actions of the circuit breaker and the relay are considered in the vector diagram of Fig. 4 wherein OE and OM respectively represent the Voltage vectors of the alternating current circuits l and 2. It will be assumed that one of these, OE, is still, while the other, OM, is rotating in the direction indicated by the arrow a; that is, approaching OE and reducing the phase difference. When the phase and frequency differences between the electromotive forces become less than the predetermined values for which the synchronizing relays 6 and H are set to respond, these relays operate. Thus it will be assumed that the relays 6 and II have their contacts closed when OM reaches the position Om preceding phase coincidence by an angle 0, where, assuming a substantially constant frequency difference, 6 is an angle corresponding to the phase change of the voltage OM during the time required for the operation of the auxiliary relay 13 after its operating coil I5 is energized and until its contacts 2d are closed; the time required for the operation of the control relay 5 after its operating coil 23 is energized by the closing of the auxiliary relay contacts 20 until the contacts 24 are closed; and also the time required by the circuit breaker 3 after its closing coil 4 is energized and until its contacts are closed. This angle 9 may be called the operating phase difference angle. In other words, at the phase angle position Om the synchronizing relays 6 and H have their contacts 9, It, and I2 closed to short-circuit the portion 22 of the resistance l4 whereby to energize fully the operating coil l5 of the auxiliary relay [3. Although the time required until the operating coil l 5 is fully energized after a portion 22 of the resistance 14 is short-circuited has been omitted in the consideration of the phase angle 6, this angle can be made larger to correspond to such added time, if necessary. In other words, the operating phase difference angle 0 can be so selected by adjustment of the relays that when OM has reached the position Om, both synchronizing relays will have their contacts closed to short-circuit the portion 22 of the resistance M whereby to energize the operating coil 15 of the auxiliary relay l3, and as OM proceeds from the position Om toward OE, the auxiliary relay l3 and the control relay 5 will successively operate, and then the operating mechanism of the circuit breaker 3 will start the closing movement so that when OM has turned far enough to coincide with OE, the operating mechanism of the circuit breaker will complete its motion and close the contacts.

While synchronizing apparatus such as described is similar to that heretofore known to the art, it has disadvantages when used in connection with alternating current circuits subject to rapid frequency changes and in high-voltage large-capacity alternating current circuits. Similar disadvantages arise in synchronizing arrangements which are dependent in part on the skill of the operator. For example, assuming that the alternating current circuits l and 2 are highvoltage large-capacity circuits, then the circuit breaker 3 used for connecting these circuits must also be of high voltage and large capacity. This means in general that a considerable length of time is required by such a circuit breaker for closing the circuit; that is, the time interval 1? plus T covering the period after the closing coil is energized until its contact is closed. In other words, when using a circuit breaker for highvoltage large-capacity circuits the operating phase difference angle 6 of the synchronizing relays has to be selected relatively large. Consequently, the possibility of the occurrence of the following difficulties is greater. Thus after the synchronizing relays have operated the frequency difference and phase difference between the electromotive forces of the circuits l and 2 may change. In other words, after OM has passed the position of Om, the angular velocity of OM may change and its direction of rotation may even reverse. Nevertheless, the circuit breaker closing operation has been started and the oper- Car ation will procede as intended to result in finally closing the breaker at an instant when OM does not coincide with OE. That is, the circuits are not in synchronism. The consequences are not only a shock to the two systems to which the two circuits belong but also to the circuit breaker itself. It will be obvious therefore that practical difiiculties arise in the application of synchronizing apparatus as described to circuits wherein the frequency is subject to rapid changes and particularly in connection with circuits requiring large relatively slowly closing circuit breakers and in synchronizing arrangements dependent on the skill of the operator.

In view of the foregoing, I propose, in accordance with my invention, to provide improved synchronizing apparatus embodying a switch for connecting two alternating current circuits and frequency dependent synchronizing devices used in the control of such switch so that the closing operation of the switch may be started without the probability of danger to circuits subject to frequency changes and also with high-voltage large-capacity circuit breakers. In accordance with my invention, I provide means dependent on the relative frequencies of the electromotive forces of the circuits I and 2 for interrupting the closing operation of the connecting means 3 when the difference between the frequencies so varies as substantially to change the time before the inphase condition occurs. Thus, as shown in Fig. 1, I provide a relay 25 responsive to the phase relation between the electromotive forces of the circuits and 2 and thus dependent on the relative frequencies of these electromotive forces, an auxiliary switch 26 on the circuit breaker 3 and suitable tripping means such as a trip coil 2'1 for the circuit breaker 3. The auxiliary switch 28 is open when the circuit breaker is open and so associated with the circuit breaker as to close when. the closing mechanism of the circuit breaker has started its closing operation or when the closing operation has advanced to some predetermined extent, such, for example, as indicated by the point A in Fig. 3. The phase difference relay 25 which is also illustrated as of the sum and difference type disclosed in the patents referred to, is connected to he energized from the poten tial transformers l and 8, and has normally closed contacts 28 which may be arranged directly in the circuit of the trip coil 21. The relay 25 is to be so set that under safe synchronizing conditions, it will open its contact 28 when OM reaches some position OP between Om and 0Q, where 0Q corresponds to the position of OM when the circuit breaker mechanism has traveled to the extent indicated by the point A in Fig. 3 and the auxiliary switch 26 is closed.

Thus, in accordance with my invention, after the synchron zing relay 6 and the auxiliary synchronizing relay I I have operated and the switch closing operation has been started, if OM has passed the position Om and the frequency difference between the electromotive forces of the circuits has not changed; that is, the speed and direction of OM have not varied, the following operations will occur: When OM reaches the position OP, the relay 25 will open its contacts 2%; and when the closing movement of the circuit breaker has progresed to the point A of Fig. 3, OM will have reached the position OQ and the auxiliary switch 26 of the circuit breaker 3 will be closed. However, as the contact 28 of the relay 25 has already opened, the trip coil 21 of the circuit breaker 3 will not be energized, and the closing operation of the circuit breaker will continue until OM reaches the inphase position OE when the contacts of the circuit breaker will close.

On the other hand, if the frequency difference between the electromotive forces of the circuits I and 2 has changed, either in magnitude or direction, after the synchronizing relays 6 and II have operated and the action for closing the circuit breaker has been started; that is, after OM has passed the position of Om, the operation will be as follows: When the closing operation of the circuit breaker mechanism has arrived at the point A, indicated in Fig. 3, the auxiliary switch 28 will be closed. At this instant, if OM is in the position OP or past it, the trip coil 21 of the circuit breaker 3 will not be energized, because the contact 28 of the relay 25 is open and the closing operation of the circuit breaker may be completed. But if at this instant OM has not reached the position OP, the trip coil 21 of the circuit breaker 3 will be energized because the contact 28 of the relay 25 is still closed. The circuit of the trip coil 21 is from one side of the control bus CB, the circuit breaker auxiliary switch 26, the trip coil 21, the contacts 28 of the relay 25, the contacts 20 of the relay I3, and the contacts I! of the relay I6 to the other side of the bus CB. Consequently, the closing operation of the circuit breaker mechanism will be interrupted or checked by tripping at an intermediate point of its travel. This supervising action continues throughout the closing motion of the mechanism. In other words, the relay 25 will re-examine the synchronous condition of the alternating current circuits I and 2 in the course of the closing operation of the circuit breaker 3 after some point, such as A, has been passed, and if the phase difference angle is smaller than the operating phase difference, angle 0 and also smaller than a predetermined angle on, it will permit the closing operation to continue, but if not, it will interrupt the closing operation and regardless of the energization of the closing coil 4, the circuit breaker 3 is tripped. Obviously, it is essential that the circuit breaker 3 be so arranged that it is either electrically or mechanically trip-free. the embodiment of my invention shown in Fig. 2, a normally open circuit-closing time limit relay 29 is connected to be energized in parallel with the operating coil 23 of the control relay 5. The

circuit closing time limit action of this relay is so chosen that it will close its contacts 30 when the closing mechanism of the circuit breaker has started its closing motion or the closing motion has advanced to a predetermined point, for example, as indicated by the point A in Fig. 3. In this embodiment of my invention, tripping of the circuit breaker will be effected if at the given point in the circuit breaker closing operation OM has not reached the position OP because the contacts 28 of the relay 25 will be closed, and the time limit relay will close its contacts 30. The tripping circuit is from one side of the control bus CB through the trip coil 21, the contacts 30 of the time limit relay 29, the contacts 28 of the relay 25, the contacts 20 of the relay I3, and the contacts I! of the relay I6 to the other side of the bus CB.

Obviously, a certain time is required from the energization of the trip coil 2'! of the circuit breaker until the circuit breaker is fully tripped. If this time corresponds to T shown in Fig. 3, then the tripping will be effected after the circuit breaker has been closed. Under certain conditions, it may be considered that even though the frequency and phase differences were to become larger, the differences would not be great. Accordingly, there might be cases where it would be more convenient not to have the tripping of the circuit breaker after the point B. In such cases, the auxiliary switch 25 of Fig. 1 or the time limit relay 25 would be arranged to close at some point between A and B such that the time before closure would be greater than the time T.

It will be obvious that in accordance with my invention I provide means for redetermining the synchronous condition in connection with the use of heretofore known synchronizing apparatus so that in the course of the closing operation of the circuit breaker, the phase difference of the electromotive forces of the circuits to be synchronized may be determined and if its value is found not less than the predetermined value at which the synchronizing apparatus is to operate, the clos-- ing operation of the circuit breaker may be immediately checked as if the operating phase difference angle were diminished from 6 to a. Therefore, synchronizing devices embodying my invention can be used without worry in circuits having large frequency variations, in high-power high-voltage alternating current circuits and in synchronizing arrangements depending at least in part on the skill of the operator.

While I have shown and described my invention in considerable detail, I do not desire to be limited to the exact arrangements shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, two alternating current circuits, means for connecting said circuits, means for actuating said connecting means, synchronizing means dependent on the relative frequencies of the electromotive forces of the circuits for initiating the operation of said actuating means before the inphase condition by a time substantially equal to the time of the closing operation of said connecting means, and means dependent on the relative frequencies of the electromotive forces of said circuits for preventing the actuating means from completing an initiated closing operation of said connecting means when the relation between the frequencies differs in a predetermined manner substantially to change the time before the inphase condition occurs.

2. In combination, two alternating current circuits, means for connecting said circuits including a circuit breaker having a trip-free operating mechanism, means dependent on the relative frequencies of the electromotive forces of the circuits for starting a closing operation of said mechanism before the inphase condition by a time substantially equal to the time of the closing operation, and means dependent on the relative frequencies of the electromotive forces of said circuits for tripping said mechanism when the relation between the frequencies differs in a predetermined manner substantially to change the time before the inphase condition occurs.

3. In combination, two alternating current circuits, means for connecting said circuits, means for actuating said connecting m ans, synchronizing means for initiating the operation of said actuating means when the phase difference and frequency difference between the electromotive forces of said circuits are below predetermined Values, and means for preventing the actuating means from completing an initiated closing operation of said connecting means when the frequency difference between the electromotive forces of the circuits differs in a predetermined manner from said predetermined value during the closing operation of said connecting means.

4. In combination, two alternating current circuits, means for connecting said circuits including a circuit breaker having a tripping mechanism, means for starting a closing operation of said circuit breaker when the phase difference and the frequency difference between the elec-' tromotive forces of said circuits are below predetermined values, and means for tripping said mechanism prior to the closing of the contacts of the circuit breaker when the frequency difference between the electromotive forces of the circuits differs in a predetermined manner from said predetermined value at a different predetermined phase difference.

5. In combination, two alternating current circuits, means for connecting said circuits, means for actuating said connecting means, synchronizing means for initiating the operation of said actuating means at a predetermined phase difference between the electromotive forces of the circuits when the frequency difference of said electromotive forces has a predetermined value, and means for preventing the actuating means from completing an initiated closing operation of said connecting means when the frequency difference between the electromotive forces differs in a predetermined manner from said predetermined value at a smaller predetermined phase difference.

6. In combination, two alternating current circuits, a trip-free circuit breaker for connecting said circuits, means for starting a closing operation of said circuit breaker when the phase difference and the frequency difference between the electromotive forces of said circuits are below predetermined values, and means for tripping said circuit breaker prior to the closing of the contacts thereof when the frequency difference between the electromotive forces of the circuits differs in a predetermined manner from said predetermined value at a smaller phase difference than that at which the closing operation was started.

7. In combination, two alternating current circuits, a trip-free circuit breaker for connecting said circuits, means for starting a closing operation of said circuit breaker when the phase difference and the frequency difference between the electromotive forces of said circuits are below predetermined values, and co-operating means for tripping said circuit breaker prior to the closing of the contacts thereof when the frequency difference between the electromotive forces of the circuits differs in a predetermined manner from said predetermined value at a smaller phase difference than that at which the closing operation was started including a circuit breaker auxiliary switch closeable at an intermediate point in the closing operation of the circuit breaker and a synchronizing relay connected to be energized from said circuits.

8. In combination, two alternating current circuits, a trip-free circuit breaker for connecting said circuits, means for starting a closing operation of said circuit breaker when the phase difference and the frequency difference between the electromotive forces of said circuits are below predetermined values, and co-operating means for tripping said circuit breaker prior to the closing of the contacts thereof, when the frequency difference between the electromotive forces of the circuits differs in a predetermined manner from said predetermined value at a smaller phase difference than that at which the closing operation was started including a trip circuit and means for controlling said tripping circuit including a synchronizing relay connected to be energized from said circuits and a time limit relay operative to complete a circuit controlling operation at an intermediate point in the closing operation of the circuit breaker.

9. In combination, two alternating current circuits, means for connecting said circuits, means for actuating said connecting means, synchronizing means for initiating the operation of said actuating means, and means dependent on the phase relation of the electromotive forces of said circuits for preventing the actuating means from completing an initiated .closing operation of said connecting means prior to actual closure.

10. In combination, two alternating current circuits, means for connecting said circuits, means for actuating said connecting means, synchronizing means for initiating the operation of said connecting means when the phase difference and the frequency difference between the electromotive forces of the circuits are less than predetermined values, means for preventing the actuating means from completing an initiated closing operation of said connecting means a predetermined time before actual closure, and means dependent on the phase relation of the electromotive forces of the circuits operative under predetermined circuit conditions to permit the completion of an initiated closing operation of said connecting means.

11. In combination, two alternating current circuits, means for connecting said circuits, means for actuating said connecting means, syn- 40 chronizing means for initiating the operation of said actuating means, means for preventing the actuatingv means from completing an initiated closing operation of said connecting means a predetermined time before actual closure, and means responsive to the phase relation between the electromotive forces of the circuits operative at a predetermined phase difference to permit the completion of an initiated closing operation of said connecting means when said phase difference occurs prior to said predetermined time.

12. In combination, two alternating current circuits, means for connecting said circuits, means for actuating said connecting means, synchronizing means for initiating the operation of said actuating means, and means dependent on the phase relation of the electromotive forces of said circuits for preventing the actuating means from completing an initiated closing operation of said connecting means when the phase difference between the electromotive forces exceeds a predetermined value at a predetermined intermediate point in the closing operation of said connecting means.

13. In combination, two alternating current circuits, a trip-free circuit breaker for connecting said circuits, means for starting a closing operation of said circuit breaker when the phase difference and the frequency difference between the electromotive forces of said circuits are below predetermined values, and means dependent on the phase relation of the electromotive forces of said circuits for interrupting the closing operation of said circuit breaker when the phase difference between the electromotive forces exceeds a predetermined value at a predetermined point in the closing travel of the circuit breaker mechanism.

SEIICHI TANIAI. 

